1. Field of the Invention
The present invention generally relates to an optical projecting system utilizing liquid crystal panels. Particularly, an optical projector utilizes reflective liquid crystal panels for saving space and simplifies the assembly and calibration of an optical projecting system.
2. Background Description
Recently, liquid crystal optical projecting system has been accepted by companies. The companies use projectors accompanying with desktop or notebook computers for visual display in meetings. The principle of the projector is directed to that the light is split to three color beams, which are a red color beam (R), a green color beam (G) and a blue color beam (B). The three color beams (R, G and B) are transmitted to three liquid crystal panels. The liquid crystal panels receive the signals from a signal source then modulates the three color beams by changing illumination and/or polarization. Further, by a dichroic prism or dichoric mirror, the three modulated color beams will be synthesized to projecting light and be transmitted through a projecting lens to a screen for carrying out the electric signals to a visual display.
FIG. 1 shows a traditional liquid crystal optical projecting system. A light source 10 outputs a light 101. The light 101 is reflected by a mirror 15a then transmitted to dichroic mirrors 16a, 16b. The light 101 is therefore split into a red beam 102, a green beam 103 and a blue beam 104. The three color beams route to lenses 14a, 14b, 14c and transparent liquid crystal panels 11, 12, 13 respectively for being modulated to a red projecting beam 106, a green projecting beam 107 and a blue projecting beam 108. After routing through dichroic mirrors 16c, 16d, the three color beams are synthesized to a projecting light 109 which can be projected broadly to a screen 18.
Another traditional liquid crystal projecting system 2 is illustrated in FIG. 2. A light source 20 illuminates a light 201. Similarly to the previous system, the light 20 is reflected and routed through the dichroic mirrors 26a, 26b then be split to a red beam 202, a green beam 203 and a blue beam 204. After being reflected through respective mirrors 25b, 25c, 25d, the three color beams are transmitted into respective lenses 24a, 24b, 24c and respective transparent liquid crystal panels 21, 22, 23 for being modulated and transformed to a red projecting beam 206, a green projecting beam 207 and a blue projecting beam 208. The three projecting beams 206, 207, 208 are emitted into a synthesizing prism 29 from different directions respectively. The synthesizing prism 29 synthesizes the three projecting beams into a projecting light 209. By a projecting lens 27, the projecting light 27 can be projected into a screen 28 with an enlarged size.
The above mentioned traditional liquid crystal projecting systems both require different dichroic prisms or dichroic mirrors for splitting a light into three color beams. By arranging positions, the three color beams are passing predetermined routes. Then the three color beams are synthesized to a projecting light via dichroic prisms, dichroic mirrors or a synthesizing prism, shown in FIGS. 1 and 2. In this case, the projecting system requires more space for containing such means and the size of the projecting system cannot be minimized, which incurs higher cost. Moreover, the process of synthesizing three color beams to a projecting light requires highly precise calibration and alignment of every element employed in the system. After satisfying the highly precision requirement, the three color beams can be synthesized perfectly. The projecting system suffers burdens due to such high precision requirements. As shown in FIG. 2, the synthesizing prism 29 includes four prisms. The beams 206, 207 and 208 emitted from three different directions are all required to pass the center line of the prism 29 in order to get good resolution. However, when a higher resolution is urged, it would be very difficult to manufacture the synthesizing prism 29 under such high precision requirements.
Furthermore, due to the traditional liquid crystal panels are independently set in different predetermined positions, it would enhance the difficulties of calibration and alignment. Especially when the resolution of the liquid crystal panel in a projecting system is required to be increased or the size of the liquid crystal panel in a projecting system is required to be minimized, the difficulty of assembly and the cost should be doubled or dramatically increased.
It is therefore an object of the present invention to provide an optical projector having a light splitting and synthesizing means with a polarization coating layer for minimizing the volume of the projecting system.
It is another object of the present invention to provide a simplified structure and assembly processes of an optical projector by integrating liquid crystal panels and supporting circuitry on a single substrate.
According to the present invention, after providing the polarization coating layer utilized in the splitting and synthesizing means, and an integrated circuit substrate having aligned liquid crystal panels and/or supporting circuitry, the volume and alignment process of the optical projector can be effectively reduced without giving up perfect resolution.